libaudio: force 8khz sample rate for VoIP input

Fixes muted mic in Viber.

Change-Id: Ie037ce633aa1fb532213f4a5d92f0ec71de81484

Conflicts:
	audio/AudioHardware.h
Merge pull request #7 from MetalDroid/patch-1

libaudio: reconcile log output with u8833